The S-IVB also ongoing to thrust at a very low stage by venting gaseous hydrogen, to help keep propellants settled inside their tanks and stop gaseous cavities from forming in propellant feed strains. This venting also preserved Protected pressures as liquid hydrogen boiled off while in the gasoline tank. https://low-power-semiconductors54207.review-blogger.com/53708017/indicators-on-apollo4-blue-plus-you-should-know